• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Rationalizing nucleation and growth in the vapor-liquid-solid (VLS) methods.
【24h】

Rationalizing nucleation and growth in the vapor-liquid-solid (VLS) methods.

机译：合理利用气液固（VLS）方法成核和生长。

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Recently, there has been an immense technological interest in the bulk growth of III-nitrides, synthesis of one-dimensional nanostructures ("nanowires") and low temperature epitaxy layers. The processes employ vapor-liquid-solid (VLS) methods in which gas phase solutes get dissolved into liquid or solvent before precipitating as solid phases. By comparision, the chemical vapor deposition (CVD) methods employ gas-solid reactions to accomplish synthesis of solid phases. However, the lack of understanding about nucleation under vapor-liquid-solid schemes limits their usefulness.; In this work, a model is proposed based on spinodal decomposition theory to understand nucleation and growth from molten metal phases in the V-L-S schemes. Furthermore, the theory is applied to rationalize both nucleation and growth of solutes from low-melting metal melts. The validation of the theory is performed through systematic experiments aimed at studying the nucleation of different solutes from lowmelting metal melts. Primarily, the experiments were conducted using binary systems involving low-melting metals as solvent and solutes such as non-reacting solutes (Si and Ge) and reacting solutes (nitrides and oxides).; The results based on the proposed model and experimental evidence suggest that nuclei diameter is primarily a function of synthesis temperature and is also dependent upon other process variables to a lesser extent. In the case of Ga-Ge and Ga-Si systems, the nucleation density of the resulting Ge nanowires increases with increasing Ga droplet diameter and decreases with increasing synthesis temperature, in agreement with the proposed model.; In the case of GaN-Ga binary system, it is determined that the interfacial energy plays a key role in the morphology of the resulting crystals. It is found that increases in hydrogen concentration in the inlet gas mixture increase the surface energy of the gallium melt thereby resulting in nanowire growth. However, it is also noted that the introduction of ammonia in the gas phase drastically reduces the surface energy of the gallium droplets owing to increased dissolution of nitrogen into the melt.
机译：近来，对III族氮化物的大量生长，一维纳米结构（“纳米线”）的合成和低温外延层具有巨大的技术兴趣。该工艺采用汽-液-固（VLS）方法，其中气相溶质在沉淀为固相之前先溶解在液体或溶剂中。相比之下，化学气相沉积（CVD）方法采用气固反应来完成固相合成。然而，由于缺乏对气液固方案下成核的理解，限制了其实用性。在这项工作中，基于旋节线分解理论提出了一个模型，以了解V-L-S方案中熔融金属相的形核和生长。此外，该理论适用于合理化低熔点金属熔体中溶质的形核和生长。该理论的验证是通过旨在研究低熔点金属熔体中不同溶质成核作用的系统实验进行的。首先，实验是使用二元体系进行的，该体系涉及低熔点金属作为溶剂以及诸如非反应性溶质（Si和Ge）和反应性溶质（氮化物和氧化物）之类的溶质。基于提出的模型和实验证据的结果表明，核直径主要是合成温度的函数，并且在较小程度上还依赖于其他过程变量。在Ga-Ge和Ga-Si系统的情况下，与所提出的模型一致，所得到的Ge纳米线的成核密度随着Ga液滴直径的增加而增加，并且随着合成温度的增加而降低。对于GaN-Ga二元体系，已确定界面能在所得晶体的形态中起关键作用。发现入口气体混合物中氢浓度的增加增加了镓熔体的表面能，从而导致纳米线的生长。然而，还应注意的是，由于增加了氮在熔体中的溶解，在气相中引入氨大大降低了镓液滴的表面能。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号